1. Field of the Invention
The present invention relates to an optical fiber array formed of multifilament type plastic optical fibers, which can be used for a light point sensor, a line point light guide or a drawing-reading optical fiber sensor head wherein evenness in the light quantity is increased.
2. Description of the Related Art
A line point optical fiber array comprising many optical fibers having their one end aligned in a line shape and their other end integrated in a circular or rectangular shape, which is valuable as a light guide, was recently developed, and this line point optical fiber array has been used for various OA machines represented by copying machines. This line point optical fiber array has a great practical value but is defective in that, since the constituent optical fibers have a circular cross-section and a diameter exceeding 200 .mu.m, the quantity of light of the line portion passing through these fibers is uneven. As a means for eliminating this light quantity unevenness, a light mixing element composed of a transparent resin is attached to the top end of the optical fiber array, but this mixing element is a main cause of a reduction of the light quantity in the optical fiber array. Moreover, since the cross-section of optical fibers aligned in the line portion as shown at 71 in FIG. 7 has a circular shape and has many dead spaces shown at 72 in FIG. 7, the light utilization efficiency as a linear light source is inevitably low.
An optical fiber array for reading optical indicators, in which one ends of optical fibers are arranged in the line form and the other ends are integrated at areas of definite addresses corresponding to the order on the line side, has been utilized mainly in the field of OA machines. In this optical fiber array, one ends of several thousands to scores of thousands of optical fibers must be arranged precisely at certain intervals in a line, and the other ends of these optical fibers must be arranged and integrated at definite positions corresponding to the arrangement positions on the line side. If the arrangement order is even slightly disturbed, a precise indicator reading becomes impossible. This arrangement operation is very difficult, and thus the ratio of a formation of defective products is very high in this operation.